This invention relates generally to semiconductor device packaging and specifically to plastic packaging of light emitting diode (xe2x80x9cLEDxe2x80x9d) arrays.
Semiconductor light emitting diodes are semiconductor chips that are mounted in a package and emit radiation in response to an applied voltage or current. These LEDs are used in a number of commercial applications such as automotive, display, safety/emergency and directed area lighting.
One type of conventional LEDs is packaged in individual, transparent shells. Each shell contains one LED chip encapsulated by an encapsulating material, such as an epoxy. However, when an array of LEDs is required for lighting applications, the individual shells are interconnected by connecting the individual LED lead frames with rigid metal lines. Such an LED array is fragile and difficult to bend into the desired shape due to the rigidity of the connecting metal lines. Thus, such an LED array cannot be easily fit into a curved lighting product, such as a round bulb.
Another type of conventional LED arrays is fabricated on a plastic substrate, as illustrated in FIG. 1. The LED chips or die 1 are physically and electrically mounted on cathode leads 3. The top surfaces of the LED chips 1 are electrically connected to anode leads 5 with lead wires 7. The lead wires are attached by known wire bonding techniques to a conductive chip pad. The leads 3, 5 comprise a lead frame and may be made of a metal, such as silver plated copper. The lead frame and LED chip array are contained in a plastic package 9, such as a LEXAN(copyright) package. The plastic package 9 is filled with an encapsulating material 13, such as a glass-filled epoxy. The package 9 contains tapered interior sidewalls 15 which enclose the LED chips 1, and form a light spreading cavity 17 which ensures cross fluxing of LED light.
However, the plastic package 9 and the lead frame 3, 5 are rigid. Thus, these LED arrays are also rigid and difficult to bend into a desired shape. These LED arrays also cannot be easily fit into a curved lighting product, such as a round bulb. The present invention is directed to overcoming or at least reducing the problems set forth above.
In accordance with one aspect of the present invention, there is provided a flexible circuit module, comprising at least one rigid carrier, at least one solid state device mounted over a first side of the at least one rigid carrier, a flexible base supporting a second side of the at least one rigid carrier, a conductive interconnect pattern on the flexible base, and a plurality of feed through electrodes extending from the first side to the second side of the at least one rigid carrier and electrically connecting the conductive interconnect pattern with the at least one of a plurality of the solid state devices.
In accordance with another aspect of the present invention, there is provided a method of forming a flexible circuit module, comprising adhering a first side of at least one rigid carrier over a first side of a flexible module base, forming a conductive interconnect pattern having a first portion over a second side of the flexible module base and a plurality of second portions extending through the flexible module base toward the at least one rigid carrier, and forming at least one solid state device on a second side of the at least one rigid carrier and in electrical contact with the conductive interconnect pattern through the at least one rigid carrier.
In accordance with another aspect of the present invention, there is provided a method of forming a packaged solid state device, comprising placing at least one conductive element into a mold cavity, filling the mold cavity with a fluid insulating material, solidifying the fluid insulating material-to form an insulating carrier, wherein at least two surfaces of the at least one conductive element are exposed after solidification, and placing at least one solid state device on the insulating carrier in contact with one surface of the at least one conductive element.